Blends compositions have been produced by blending polysulfones with polycarbonates. See for example U.S. Pat. No. 3,365,517. The polycarbonates used in these blends were generally prepared from dihydroxy compounds in which hydroxy-substituted aromatic rings are typically bridged by an alkylene or alkylidene radical. Bisphenol-A is the primary example of such a conventional bisphenol. While polycarbonates were recognized to provide molded articles with desirable combinations of physical and optical properties, the polysulfone imparted a superior level of rigidity, hydrolytic stability and heat resistance to such articles. The blends according to U.S. Pat. No. 3,365,517 were not, however, transparent and it would be desired to provide molded articles with improved combinations of transparency and physical properties.
It is also known that copolymers can be prepared comprising carbonate and sulfone moieties. In these copolymers a range of dihydroxy compounds have been employed including fluorene-bridged aromatic dihydroxy compounds. See for example Japanese Patent Publication JP 05-163,350. These polymers are taught to have good combinations of properties, including transparency, but require a different synthesis of an expensive new polysulfone copolymer for adjusting polymer properties.
It would be desirable to provide resins which, in the form of molded articles, have improved combinations of properties. In many applications, such as the medical field, it is extremely important for molded articles to have good transparency and hydrolytic stability in addition to other performance characteristics. It would accordingly be desirable to obtain compositions containing polycarbonate and polysulfone from which a transparent article could be molded having good combinations of impact resistance, ductility and hydrolytic stability.